Robust MIMO Design of Decentralized Voltage Controllers of PV Systems in Distribution Networks

In the last few years distribution networks have been integrating grid-connected photovoltaic (PV) systems, which can actively participate to help flatten the feeders voltage profile by injecting reactive power. However the contemporaneous operation of the PV systems may cause problems in voltage regulation and stability. To solve these issues the present paper illustrates a design methodology of decentralized voltage controllers acting on the PV reactive power injections. Each controller has only two fixed parameters and uses only local information without the need of data exchange with the other controllers. The design is based on a structural dynamic multiple-input multiple-output (MIMO) model of the distribution system and guarantees efficient voltage support and stable behavior in the presence of parameters uncertainty and unmodeled dynamics affecting the MIMO model. To validate the effectiveness of the proposed design, the results of numerical simulations are carried out for a test distribution system under different operating conditions.